trpmb6
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Wed Jul 11, 2018 8:16 pm

I'm trying to find an FAA reference to external fuel tanks as I've always been under the impression it's a big no-no for part 25 aircraft. Having little luck at the moment.

I can tell you that a major concern for external fuel tanks is bird strikes.
 
Karlsands
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Wed Jul 11, 2018 8:17 pm

Go buy a FAR-AIM book if it’s that hard to find , geez
 
trpmb6
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Wed Jul 11, 2018 8:27 pm

That's the thing, i'm not finding any references in the fars and haven't come across an AC yet with it. So either it is an issue and I haven't found it yet, or it really isn't an issue and something that I've always thought was the case was a total house of cards crumbling around me now.
 
JoeCanuck
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Wed Jul 11, 2018 8:45 pm

trpmb6 wrote:
That's the thing, i'm not finding any references in the fars and haven't come across an AC yet with it. So either it is an issue and I haven't found it yet, or it really isn't an issue and something that I've always thought was the case was a total house of cards crumbling around me now.


Wing tanks aren't really internal. They are basically a thin layer of aluminum away from the elements, impact and 1500 degree engines. Besides, there are plenty of examples of civil aircraft with tip tanks and the Jetstream had mid wing tanks.

I'm not trying to sell the idea so much as discuss the concept. External tanks are certainly one way to solve the problem of where to store fuel. Whether or not it's a good idea may very well be up for debate.
What the...?
 
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Erebus
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Wed Jul 11, 2018 10:40 pm

Would there be enough space inside the horizontal stabilizers to store meaningful amounts of fuel?
 
tealnz
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 12:00 am

Erebus wrote:
Would there be enough space inside the horizontal stabilizers to store meaningful amounts of fuel?

I seem to recall comments from experts on here saying it wasn't really a runner for A320s. Weight of piping, pumps, COG management issues...
 
d8s
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Re: Airbus is studying A321XLR to challenge Boeing

Thu Jul 12, 2018 12:35 am

imthedreamliner wrote:
Can this aircraft compete with MOM from Boeing ?


No it probably can't, but Airbus will milk the A32X model for as much as it can much like Boeing has with the 737 family. No clean sheet will come out of "A" until the EU governments float it some cash.
 
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keesje
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 4:49 am

I can see Airbus launching a significantly more capable A321 version this year. Regardless of what Boeing does or does not.
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seahawk
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 4:57 am

And where should they find those capabilities?
 
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keesje
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 5:03 am

seahawk wrote:
And where should they find those capabilities?


10% more wingspan, thrust, seats & range. No cleansheet, taxcut give-aways or import protectionism required.
"Never mistake motion for action." Ernest Hemingway
 
YYZatcboy
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 5:15 am

Is there a way instead of putting fuel in the Hstab to put it in the VStab? Presumably more volume could be put there than in the H stab. And I guess if you are running the ducting and valves, may as well put it in the Hstab and V Stab. Is there a technical reason not to put fuel in the Vstab?
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 5:26 am

keesje wrote:
seahawk wrote:
And where should they find those capabilities?


10% more wingspan, thrust, seats & range. No cleansheet, taxcut give-aways or import protectionism required.


Which kind of conflicts with the news from Airbus that they shelved the more advanced A321 upgrades for the moment.
 
rheinwaldner
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 5:52 am

trpmb6 wrote:
That's the thing, i'm not finding any references in the fars and haven't come across an AC yet with it. So either it is an issue and I haven't found it yet, or it really isn't an issue and something that I've always thought was the case was a total house of cards crumbling around me now.


Browsing images instead of documents, I found this:
Image

And this:


seahawk wrote:
Which kind of conflicts with the news from Airbus that they shelved the more advanced A321 upgrades for the moment.

Which conflicts with what Enders said these days. And .... compare the authority of those, who said "it is shelved" with the authority of Enders: "unnamed sources" vs CEO... :)
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77H
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 6:01 am

Karlsands wrote:
Go buy a FAR-AIM book if it’s that hard to find , geez


Sheesh. Remove the stick from your posterior. No need for the attitude.
 
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seahawk
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 6:03 am

rheinwaldner wrote:
Which conflicts with what Enders said these days. And .... compare the authority of those, who said "it is shelved" with the authority of Enders: "unnamed sources" vs CEO... :)


No it does not, as Enders points out that there is still lots of potential in the A321, but does not specify a time frame when Airbus will bring that to the market. A launch in 2019 (most likely at Paris in June) would require the design to be finished today and the authority to offer would need to come in the next 3 months. I think that would have leaked by now.
 
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 6:45 am

seahawk wrote:
rheinwaldner wrote:
Which conflicts with what Enders said these days. And .... compare the authority of those, who said "it is shelved" with the authority of Enders: "unnamed sources" vs CEO... :)


No it does not, as Enders points out that there is still lots of potential in the A321, but does not specify a time frame when Airbus will bring that to the market.

No, it very well does. And not only does the April article stand in conflict, with what Enders said, Enders even exposed it as fake news. Enders specifically mentioned people (="engineers") who worked on A321 upgrade studies. So the heavily pushed and defended notion by many commenters, that all the Airbus engineers have been sent to the shop-floor to solve problems instead of planning A320 upgrades (based on the April article) simply was wrong. Enders this time said in presence tense, "Airbus is conducting several studies". How does that not conflict with "Airbus has shelved the A320P and A320PP studies"?
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seahawk
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 6:54 am

Well that always was a very extreme interpretation of the rumours. Especially as the the meaning of "to shelve" is very different in German/French to the typical US/English meeting.

In English it rather means that the project has been cancelled, in the German/French it does more imply that you have every intention to go ahead, just not right now.
 
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aerolimani
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 7:37 am

I think I found a rendering!
Image
 
oslmgm
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 7:50 am

aerolimani wrote:
I think I found a rendering!
Image

Lol, that is an XLR plane. Certainly balanced. And female - I guess all planes are?
 
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Taxi645
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 8:10 am

rheinwaldner wrote:
seahawk wrote:
rheinwaldner wrote:
Which conflicts with what Enders said these days. And .... compare the authority of those, who said "it is shelved" with the authority of Enders: "unnamed sources" vs CEO... :)


No it does not, as Enders points out that there is still lots of potential in the A321, but does not specify a time frame when Airbus will bring that to the market.

No, it very well does. And not only does the April article stand in conflict, with what Enders said, Enders even exposed it as fake news. Enders specifically mentioned people (="engineers") who worked on A321 upgrade studies. So the heavily pushed and defended notion by many commenters, that all the Airbus engineers have been sent to the shop-floor to solve problems instead of planning A320 upgrades (based on the April article) simply was wrong. Enders this time said in presence tense, "Airbus is conducting several studies". How does that not conflict with "Airbus has shelved the A320P and A320PP studies"?


It's not ideal though for Airbus that Boeing's tippy toeing with the NMA is postponing the transistion from studies to products entering service. All the while that till 2028-ish they'll have a A330 replacement to attend to, a possible A380 update and possible headaches regarding how they will integrate even higher bypass GTF engines onto the A350 frame extending it's range beyond what is necessary.

Every day further delaying A320 developments entering into service because of NMA waiting is an extra day removed from the time available for all the above to be realized and another day for the 737 to extend it's lifetime.

I'm not saying it is the wrong choice by Airbus, it most likely isn't. Just that is a consequence of the NMA waiting.
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seahawk
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 8:22 am

Boeing plays a very small part in the decision. The big point is that there are dozens of A320NEO gliders waiting for their engines sitting at Airbus factories and that the whole NEO ramp-up is behind schedule due to the engine problems and given the backlog and the current production capacity, there are no slots Airbus could offer for a new variant till 2023+. So it makes a lot of sense to first make sure that the engines are finally working (because a A321++ with ETOPS 60 would be pretty pointless) and that you can actually deliver the planes in a reasonable time frame and more importantly on time, so that you do not pay high penalties to the launch customers. I think 2020 they will launch and they will still start delivering before the 797 does.

Is it not interesting that Airbus has not thrown P&W under the bus for all the delays they had to take for the A320NEO - especially when you consider the relationship to Zodiac when they could not meet their delivery schedule.
 
mjoelnir
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 10:06 am

seahawk wrote:
Boeing plays a very small part in the decision. The big point is that there are dozens of A320NEO gliders waiting for their engines sitting at Airbus factories and that the whole NEO ramp-up is behind schedule due to the engine problems and given the backlog and the current production capacity, there are no slots Airbus could offer for a new variant till 2023+. So it makes a lot of sense to first make sure that the engines are finally working (because a A321++ with ETOPS 60 would be pretty pointless) and that you can actually deliver the planes in a reasonable time frame and more importantly on time, so that you do not pay high penalties to the launch customers. I think 2020 they will launch and they will still start delivering before the 797 does.


I believe that Airbus is working on further evolutions on the A320 family. Not only on size and range, but also on changes to lighten current frames. There is the project to replace hydraulic with electro hydraulic actuators for example, the all electric wing test flown on the MSN001 before she was retired. I think implementation has been shelved, rather than development and we will see new things, when the ramp up is under control.

seahawk wrote:
Is it not interesting that Airbus has not thrown P&W under the bus for all the delays they had to take for the A320NEO - especially when you consider the relationship to Zodiac when they could not meet their delivery schedule.


If Airbus has decided, that having the GTF future proofs the A320neo family, they will rather help P&W, instead of throwing them to the wolves.
 
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seahawk
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 10:31 am

mjoelnir wrote:
seahawk wrote:
Boeing plays a very small part in the decision. The big point is that there are dozens of A320NEO gliders waiting for their engines sitting at Airbus factories and that the whole NEO ramp-up is behind schedule due to the engine problems and given the backlog and the current production capacity, there are no slots Airbus could offer for a new variant till 2023+. So it makes a lot of sense to first make sure that the engines are finally working (because a A321++ with ETOPS 60 would be pretty pointless) and that you can actually deliver the planes in a reasonable time frame and more importantly on time, so that you do not pay high penalties to the launch customers. I think 2020 they will launch and they will still start delivering before the 797 does.


I believe that Airbus is working on further evolutions on the A320 family. Not only on size and range, but also on changes to lighten current frames. There is the project to replace hydraulic with electro hydraulic actuators for example, the all electric wing test flown on the MSN001 before she was retired. I think implementation has been shelved, rather than development and we will see new things, when the ramp up is under control.

seahawk wrote:
Is it not interesting that Airbus has not thrown P&W under the bus for all the delays they had to take for the A320NEO - especially when you consider the relationship to Zodiac when they could not meet their delivery schedule.


If Airbus has decided, that having the GTF future proofs the A320neo family, they will rather help P&W, instead of throwing them to the wolves.


I agree with you. But the relationship with P&W is imho interesting as P&W claims that there is a bit more thrust in the GTF and that would be quite nice to have for an A321+ or A322. (or imagine they would have talked about upgrading the hot section and delivering a serious pip around 2023 - P&W must have looked studied their option for a 797 bid anyway)

Imagine a A321++ / A322 with a generation 1.5 GTF, carbon wingbox, new wing and more electric system architecture. That is exactly the kind of product that will make the business case for the 797 difficult.
 
M564038
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 11:04 am

This is a very valid point!
Easy to forget for people with english as first language that «shelved» does not mean dropped!
It literally, and in most languages, means something that you are not going to use right now, but it is still there. On the shelf. For use.

seahawk wrote:
Well that always was a very extreme interpretation of the rumours. Especially as the the meaning of "to shelve" is very different in German/French to the typical US/English meeting.

In English it rather means that the project has been cancelled, in the German/French it does more imply that you have every intention to go ahead, just not right now.
 
WIederling
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 11:15 am

M564038 wrote:
This is a very valid point!
Easy to forget for people with english as first language that «shelved» does not mean dropped!


Even hitches around for "native" speakers. cue: "tabled", "you are through", ..

( someone got more examples of EN || US English mismatch? )
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masi1157
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 11:18 am

M564038 wrote:
It literally, and in most languages, means something that you are not going to use right now, but it is still there. On the shelf. For use.

There is no "to shelve" in german, there is not even a literal translation of it in use. But regarding the A320neo+ everybody here said something like "auf Eis gelegt" (put on ice), which of course means you put it aside but preserve it for later use.


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M564038
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 12:02 pm

My first language is a different germanic language very close to german, and we use both ice and shelf.
None of them means dropped.


masi1157 wrote:
M564038 wrote:
It literally, and in most languages, means something that you are not going to use right now, but it is still there. On the shelf. For use.

There is no "to shelve" in german, there is not even a literal translation of it in use. But regarding the A320neo+ everybody here said something like "auf Eis gelegt" (put on ice), which of course means you put it aside but preserve it for later use.


Gruß, masi1157
 
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Revelation
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 12:02 pm

masi1157 wrote:
M564038 wrote:
It literally, and in most languages, means something that you are not going to use right now, but it is still there. On the shelf. For use.

There is no "to shelve" in german, there is not even a literal translation of it in use. But regarding the A320neo+ everybody here said something like "auf Eis gelegt" (put on ice), which of course means you put it aside but preserve it for later use.

I agree with this interpretation. Some members were offended by the suggestion and took any notion of deviation from plan as being a slur against their favored vendor. The rest of us know that plans change and it would be pretty unsound to tell customers about the A320+/++ whilst TLS and XFW are loaded with NEO gliders that those same customers are left waiting for and dealing with groundings like the ones in India. The reports did not say that any/all A320 enhancement work was discarded and any hope of future A320 developments was now null and void. Some members used exaggeration for effect and threw out lots of senseless strawman arguments as a smokescreen to mask their hurt egos. It's been pretty amusing to watch, IMHO.

We have a long running 'shelved' thread, seems we should use this one for news of the kind that we just got from Herr Enders, no?

The quote was:

tealnz wrote:
What additional potential is in the A321neo? Airbus is conducting several studies, including an XLR with even more range than the A321LR. I have to say I am amazed how much extra potential our engineers have found in the A321 over the last few years and how much more they could realize. I don’t want to reveal too much, but when I say that we are relaxed about the NMA, that has a lot to do with the additional potential we see in the A321neo.

Clearly lots of potential has been found in the A321 over the last few years, we do have A321NEO and A321NEOLR after all. And there's "much more" left seems to be a given, especially if you're willing to spend on an all new wing, but of course he doesn't want to say too much till they're ready to make announcements.

Yet if he has to make this statement, he's not relaxed about the NMA, he's quite concerned about it. Otherwise why would he want to risk undermining the huge backlog of A321s he already has by suggesting they're already inferior in capabilities to ones his team is already studying?
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seahawk
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 12:12 pm

Revelation wrote:
Yet if he has to make this statement, he's not relaxed about the NMA, he's quite concerned about it. Otherwise why would he want to risk undermining the huge backlog of A321s he already has by suggesting they're already inferior in capabilities to ones his team is already studying?


Because saying our current product is great, but we will make it even better is preferable to saying "our current product is completely at the limits of what can be done with it".
 
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 12:34 pm

seahawk wrote:
Revelation wrote:
Yet if he has to make this statement, he's not relaxed about the NMA, he's quite concerned about it. Otherwise why would he want to risk undermining the huge backlog of A321s he already has by suggesting they're already inferior in capabilities to ones his team is already studying?

Because saying our current product is great, but we will make it even better is preferable to saying "our current product is completely at the limits of what can be done with it".

As we say in the US, "as if!". Of course he would not say that. Boeing still finds ways to enhance 737s. It should be a given that all products have room for improvement. The real question is why would you be talking about improvements when you have a huge backlog and your biggest problem is how to build the current models faster and cheaper? Unless of course you fear a competitor's product...
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 12:46 pm

Revelation wrote:
seahawk wrote:
Revelation wrote:
Yet if he has to make this statement, he's not relaxed about the NMA, he's quite concerned about it. Otherwise why would he want to risk undermining the huge backlog of A321s he already has by suggesting they're already inferior in capabilities to ones his team is already studying?

Because saying our current product is great, but we will make it even better is preferable to saying "our current product is completely at the limits of what can be done with it".

As we say in the US, "as if!". Of course he would not say that. Boeing still finds ways to enhance 737s. It should be a given that all products have room for improvement. The real question is why would you be talking about improvements when you have a huge backlog and your biggest problem is how to build the current models faster and cheaper? Unless of course you fear a competitor's product...


The desire for something to fill the gap between the A321 and A330 will have been noticed by Airbus regardless of whatever Boeing comes up with. In other industries it is completely normal to talk about new products long before they arrive. Look at the car industry and all those fancy car studies they show to the customer. In the end it is the same logic,you have identified a possible market segment that you consider as big enough to make a business case. Then you show your ideas to the customer to get feedback. For that you must expose your plans. If the feedback is positive you go ahead and develop and launch the product, if not you adjust the concept or scrap it. I am certain that Airbus has shown the potential customers their design studies, so they already know what Airbus is up to and therefore he can talk about it. Even in the public domain it is hardly a secret any more. So just because we have a duopoly does not mean that both players only act because the competition does. Both act when they see a chance to improve their position.
 
tealnz
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 12:50 pm

Revelation wrote:
As we say in the US, "as if!". Of course he would not say that. Boeing still finds ways to enhance 737s. It should be a given that all products have room for improvement. The real question is why would you be talking about improvements when you have a huge backlog and your biggest problem is how to build the current models faster and cheaper? Unless of course you fear a competitor's product...

Airbus are a business. They have scale but they will always want more margin. The 321LR lets them take a slice of a new, higher-margin market segment. More range would let them take even more of that segment (eg for more skinny trans-Atlantic or Asian point-to-point routes). Sounds as if they have identified a way of getting substantially more range out of the LR that wasn't available when they did the original LR development. Something that lets them own a segment that Boeing won't be able to compete in for some time, if at all. Fear? Sounds to me more like hunger to win and prosper.
 
divemaster08
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 3:26 pm

While not exactly a large space, would it be possible to add fuel into the horizontal and vertical stabilizer? maybe to much of a change to the CFG, also not sure how much volume one could get out of the A321 empennage.
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 8:09 pm

trpmb6 wrote:
I'm trying to find an FAA reference to external fuel tanks as I've always been under the impression it's a big no-no for part 25 aircraft. Having little luck at the moment.

I can tell you that a major concern for external fuel tanks is bird strikes.


JoeCanuck wrote:
trpmb6 wrote:
That's the thing, i'm not finding any references in the fars and haven't come across an AC yet with it. So either it is an issue and I haven't found it yet, or it really isn't an issue and something that I've always thought was the case was a total house of cards crumbling around me now.


Wing tanks aren't really internal. They are basically a thin layer of aluminum away from the elements, impact and 1500 degree engines. Besides, there are plenty of examples of civil aircraft with tip tanks and the Jetstream had mid wing tanks.

I'm not trying to sell the idea so much as discuss the concept. External tanks are certainly one way to solve the problem of where to store fuel. Whether or not it's a good idea may very well be up for debate.


divemaster08 wrote:
While not exactly a large space, would it be possible to add fuel into the horizontal and vertical stabilizer? maybe to much of a change to the CFG, also not sure how much volume one could get out of the A321 empennage.


For sure, before considering any exotic tanks like conformal fuel tanks or underwing tanks, it would make sense for Airbus to try to make use of the volume of the HTP and VTP. I see some benefits as well as some challenges using the tail planes.

The benefits I can think of (compared to the current A320/321 design):
- B1: extra tank volume without compromising the volume available for bagages & cargo. Regarding the volume of these areas, here are my quick (and not too dirty) estimates; (1) VTP torque box: 10 sq.m area times 0.25 m average thickness gives 2.5m³. Let's remove 20 to 30% for internal structure and systems, this leaves 1.75 - 2m³. (2) HTP torque box: about the same torque box area and slightly thinner than the VTP (going by the sketches in the A321 AIRCRAFT CHARACTERISTICS AIRPORT AND MAINTENANCE PLANNING). Let's assume 1.5m³ in the HTP. All in all, the tail planes would be good for 3m³, that's the equivalent of 1 ACT.
- B2: this new tank could easily benefit the entire product line, not just the A321NEO-LR, even though the A321 is the prime candidate for additional fuel volume.

- (B3): I've found an Airbus presentation stating that "For Single Aisle aircraft, NO effect of CG position on fuel consumption". I still need to dig a bit to understand why it is so, but let's consider for now that adding weight in the tail wouldn't provide any benefit on the fuel consumption. (Ref: "Optimum CG position -What is the best CG position for an aircraft ?", Catherine Bonnet, Flight Operations, Weight and Balance Engineer; Airbus, 2009)

Some challenges:
- C1: converting the tail planes into fuel tanks would require an extensive redesign of the fuel systems. It would require some time and money to be certified.
- C2: as pointed by divemaster08, adding a few tons of fuel in the back of the aircraft would affect the weight balance. I'm not able to elaborate further on this issue.
- C3: this expended fuel systems would add weight and cost to the aircraft, including extra maintenance cost. They could only be justified for customers that would regularly take advantage of this extra fuel capacity. It should be seen as an option, but in this case, this is adding manufacturing complexity. Note that being integral fuel tanks, the weight penalty is mainly with the extra piping and pumps, which might not be worse than the empty weight of an ACT.

All in all, there is some potential in turning the tail planes into fuel tanks, but is it worth the investment for Airbus and the extra-burden for the airlines? If the demand for an A321-XLR is sufficient, the answer could be positive provided that this feature would remain optional. This is just me thinking.

Now, coming to the exotic design of underwing fuel tanks, here are some thoughts:
- looking at the typical fighter jet external fuel tanks, considering external tanks in the range of 1.5 to 2m³ each doesn't seem out of proportion for the A320 wing.
- I observe that Airbus has already adapted the A330 wing to install an underwing refueling pod and the associated pylon. It gives us a very good idea of the design of such an installation. The A400M wing also has structural provisions to install a refueling pod.
- external features come with a drag penalty and a weight penalty in comparison with integral fuel tanks. It is less so versus ACTs.
- underwing tanks are beneficial for the bending moment of the wing compared to the use of ACTs.
- being directly connected to the wing tank, an underwing tank wouldn't add much complexity to the fuel system
- there are indeed challenges regarding bird strikes, especially at > 0° AoA. This is mainly adding some weight to this tank, but doesn't render it infeasible.
- I would see this tank slightly outboard of the engine, maybe in line with the fairing of the 3rd flap track, or slightly further outboard at the split line between slats 2 and 3.
- someone raised the point of the FAR part-25. There seem to be no mention of external fuel tank, but here is a requirement that think is relevant in the context of this discussion. I've found it in Section 963 - Fuel tanks: general.
"(d) Fuel tanks within the fuselage contour must be able to resist rupture and to retain fuel, under the inertia forces prescribed for the emergency landing conditions in §25.561. In addition, these tanks must be in a protected position so that exposure of the tanks to scraping action with the ground is unlikely."
An external fuel tank located as I suggested above could be pretty well be protected by the (large) engine from scraping action with the ground in the event of a belly landing or landing with one failed main landing gear. Only more catastrophic landings that would take an engine away might expose the external fuel tank to scraping and most probably a non-survivable impact (for the tank I mean). This latter scenario might raise a red flag for this design but I'd welcome a more educated input at this stage.
- I had a thought about using underwing tanks for something else than fuel, in particular non-flammable fluids. This in order to make more room for fuel inside the fuselage. All I can think of are the water tank and waste water tank but both are fairly small volume even on an A321 and would require complex if not impossible piping redesign. This is definitely not worth investigating further. On the other hand, external tanks would be too small to provide any meaningful cargo volume (note that "baggage tanks" exist for fighter jets).
 
JoeCanuck
Posts: 4424
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Thu Jul 12, 2018 8:47 pm

One of the things I like about the idea of 'external' fuel tanks, is that they don't take up valuable pressurized volume.

External wing/fuselage fuel storage makes sense to me because it can keep the fuel nearer the CofG, and the tank wouldn't interfere with other systems.

I'm sure some tail volume could be converted to fuel storage, but I can see a bunch of engineering issues. There's the CofG issues as well as strengthening a relatively small structure to handle the extra mass. The horizontal stab not only moves, but contains dozens more moving pieces that would have to be redesigned to work with a fuel tank. Being a control surface, it is subject to all sorts of aerodynamic and mechanical forces so any change could result in serious flutter and fatigue issues. Look at the problems the 748 had with its horizontal stab tank.

To me, non moving tanks, (perhaps removable if range wasn't needed), would be a better solution with conformal wing root tanks seeming like a possibility, especially since the concept has been proven in military applications. Granted, military requirements are often different than civilian, but wouldn't it be nice to keep that hold open for cargo?
What the...?
 
Turnhouse1
Posts: 81
Joined: Tue Jun 16, 2015 5:57 pm

Re: Reuters: Airbus is studying A321XLR with extended range over LR

Sat Jul 14, 2018 5:03 pm

Article below is mostly about Brexit and the potential of Airbus moving production away from the UK. However, towards the end there is interesting discussion that Airbus are working on a carbon fibre folding wing for a next gen A320. Looks like they want the aero improvement but to still fit into the same gates.

"“We’re developing a folding wing tip,” he said. “On a single-aisle jet like the A320, this gives a longer wing and is more aerodynamic, but it will also fit into the airport gate when folded.”"

https://www.theguardian.com/business/20 ... CMP=twt_gu
 
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Revelation
Posts: 18159
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Sat Jul 14, 2018 5:32 pm

Turnhouse1 wrote:
Article below is mostly about Brexit and the potential of Airbus moving production away from the UK. However, towards the end there is interesting discussion that Airbus are working on a carbon fibre folding wing for a next gen A320. Looks like they want the aero improvement but to still fit into the same gates.

"“We’re developing a folding wing tip,” he said. “On a single-aisle jet like the A320, this gives a longer wing and is more aerodynamic, but it will also fit into the airport gate when folded.”"

https://www.theguardian.com/business/20 ... CMP=twt_gu

This isn't the first such report.

Where there's smoke, there's fire.

Should be interesting to see if Brexit impacts this or not.

Given what Enders recently said:

May’s administration has “no clue or consensus on how to execute Brexit without severe harm,” Enders said at a briefing in London Friday. The confusion has wasted months of negotiating time and created “a discomforting situation” for the planemaker, he added.

Enders said in his latest comments that the U.K. should at least stay in the customs union and various regulatory bodies and agree to abide by European Court of Justice decisions.

“This is the minimum I think to keep the business,” he said. “Not harmless, but to minimize the damage to business.” The CEO added that he was speaking out “not because we want to play politics” but because the company has a duty to stakeholders “to be truthful about the consequences.”

... it seems we shouldn't be presuming the new CFRP wings will be built in the UK.
Wake up to find out that you are the eyes of the world
The heart has it's beaches, it's homeland and thoughts of it's own
Wake now, discover that you are the song that the morning brings
The heart has it's seasons, it's evenings and songs of it's own
 
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JetBuddy
Posts: 1946
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Sat Jul 14, 2018 5:59 pm

Revelation wrote:
... it seems we shouldn't be presuming the new CFRP wings will be built in the UK.


It could swing both ways. The US might offer a very reasonable trade deal with the UK, far more open and unrestrictive than the one with the EU. At least that's the rumor. This could generate more Airbus parts production meant for the Alabama plant. Everything is up in the air at this time, no pun intended.
 
oslmgm
Posts: 167
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Sat Jul 14, 2018 8:28 pm

Turnhouse1 wrote:
Article below is mostly about Brexit and the potential of Airbus moving production away from the UK. However, towards the end there is interesting discussion that Airbus are working on a carbon fibre folding wing for a next gen A320. Looks like they want the aero improvement but to still fit into the same gates.

"“We’re developing a folding wing tip,” he said. “On a single-aisle jet like the A320, this gives a longer wing and is more aerodynamic, but it will also fit into the airport gate when folded.”"

https://www.theguardian.com/business/20 ... CMP=twt_gu


Lots of interesting stuff that I haven't heard before in that article. They started design work on a new wing 18 months ago, and...:
The current wing span for an A320 is 36 metres; Airbus is considering a span of between 40 and 44 metres for the folding wing.

(...) the new wing will create drag improvements of 12%. (...)

When the future wing goes into production – which will be within the next 10 years (...)


Into production within 10 years, wouldn't that imply a launch within about 5 years?
 
parapente
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Joined: Tue Mar 28, 2006 10:42 pm

Re: Reuters: Airbus is studying A321XLR with extended range over LR

Sat Jul 14, 2018 9:05 pm

There has been intense discussion on this forum as to whether the 797 will sport folding wings.Perhaps this revelation ( which looks like a response to the 797 ( plus plus) indicates that the Boeing product is indeed using the same (777x) technology.
 
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Taxi645
Posts: 173
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Sat Jul 14, 2018 9:35 pm

Well the article does seem to indicate that the WHOLE A320 line will benefit from this new composite wing not just the types competing with the bottom of the NMA (although the article hints towards a 40m+ folding wing rather than a 36m meter one).

As said to me this makes a lot of sense. Not only does it improve the viability as a NMA competitor it also at the same time put's a lot of pressure on the 737.

Further advantages:
-Weight savings
-Strongly increased in wing fuel volume
-many aerodynamic advantages
-in turn requiring less thrust to much more capabaility increase without engine change.

Sure it is expensive, but given it not only strongly improves performance but additional gives the large strategic advantages of being able to better compete with both the 737 AND 797 improves the bussines case immensly.


Shorter term I see launching an A220-500 sooner rather than later as possibility to put pressure on Boeing without having to wait on an NMA deciscion. What Airbus does with the A320 line is more dependant on the NMA/NSA deciscion than for the A220. In any case a possible NSA is more likely to move away from the A220 size. Sure it will not be easy to increase production scale of the A220, but I suspect that will be one of the priorities at Airbus.By doing so Airbus would achieve several things:

-add a product that will most likely have a definitive market
-increasing production rate will give economy of scale for the A220
-expand market share where the production limited A320 can't (it is risk reducing and stability increassing to distribute production scale over both models rather than having it so strongly dependant on the A320)
-make it harder for newcomers to enter the market..


For all the above Airbus will depedend on engine makers to be able to scale reliably to significantly higher levels. Perhaps an opportunity for RR to re-enter?

seahawk wrote:
Is it not interesting that Airbus has not thrown P&W under the bus for all the delays they had to take for the A320NEO - especially when you consider the relationship to Zodiac when they could not meet their delivery schedule.


Indeed.


Revelation wrote:
Yet if he has to make this statement, he's not relaxed about the NMA, he's quite concerned about it. Otherwise why would he want to risk undermining the huge backlog of A321s he already has by suggesting they're already inferior in capabilities to ones his team is already studying?



That huge backlog is the reason there is more room to spoil the beens. Sales are mostly production limited. By hinting at A320 developments he can add doubt to potential NMA customers at less risk than he could when if it wasn't prodcution limited.
Innovation is seeing opportunity before obstacle.
 
JoeCanuck
Posts: 4424
Joined: Mon Dec 19, 2005 3:30 am

Re: Reuters: Airbus is studying A321XLR with extended range over LR

Sat Jul 14, 2018 10:00 pm

Folding wingtips, more than any other modification, have made the 77X program a reality. They will allow a heavier plane fly further on less fuel with smaller engines. The program doesn't get off the ground, (I know...), without them. Airbus knows as well as Boeing, that greater wingspan can make for a more efficient aircraft but the limiting factors have been gate size and ground handling clearance. Folding wings can provide a low(ish) tech concept with a lot of reward for relatively little risk.

It's basically a locking hinge. There are dozens of them on every aircraft. I'm a bit surprised it has taken so long to get them into commercial service and even more surprised when I see resistance to the concept.

Now that Boeing has made folding wings OK, it is only logical for everybody to consider them.
What the...?
 
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Matt6461
Posts: 2706
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Re: Reuters: Airbus is studying A321XLR with extended range over LR

Sun Jul 15, 2018 12:31 am

Turnhouse1 wrote:
Article below is mostly about Brexit and the potential of Airbus moving production away from the UK. However, towards the end there is interesting discussion that Airbus are working on a carbon fibre folding wing for a next gen A320. Looks like they want the aero improvement but to still fit into the same gates.

"“We’re developing a folding wing tip,” he said. “On a single-aisle jet like the A320, this gives a longer wing and is more aerodynamic, but it will also fit into the airport gate when folded.”"

https://www.theguardian.com/business/20 ... CMP=twt_gu


Awesome. Thanks.

For a couple years now I've been saying we might not see an NSA - at least from Airbus - for another 40 years. If Airbus launches an A320NG with 30% fuel savings over Neo - possible given ~15% SFC delta and ~12% L/D delta - then we're talking ~150seat-mi/gal for LCC A321 operators. That means ~10gals/pax for a 2hr flight.

At this level of fuel efficiency, only astronomical gas prices justify paying a premium for NSA over A320NG. A 10% fuel delta saves ~$2.25/seat at today's prices, $4 at $4/gal kerosene.

Meanwhile, 4hrs block time costs ~$4k for A321neo, which means ~$20/seat for a 200-seat layout. The NSA can only charge 20% premium if gas is $4/gal; any less than than that it's better to buy a cheaper older-tech A320NG.

Could Boeing respond with a 5th-gen 737? I guess so but program cost would almost certainly be higher than Airbus' (new MLG and more fuselage revision) and would be so close to NSA that you might as well do NSA.

...but as I say above, it's hard to get a price premium sufficient to justify the massive investment required.

And with China spooling up its aviation industry at durably lower cost, the acquisition cost competition becomes even more severe.

All of which is to say that NMA might be Boeing's last clean sheet project in the sub-300seat space for decades or ever. And NMA should be positioned above a product niche - shorthaul planes - that foreseeably will reach the low-margin commoditization equilibrium that, say, small sedans have reached in the car business ( where u.s. companies are withdrawing from it entirley).

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